Conjugated conducting polymers displaying moderate charge mobilities, an ability to be redox doped to highly conducting compositions, and an ability to change optical properties reversibly, can be used as color changing materials, conductors, and antistatic coatings in electronic components, photovoltaic devices, and light emitting devices. One class of conducting polymers, polyheterocycles, which include polythiophenes, polypyrroles, and polyfurans, have been developed for their use in electrochromic devices, photovoltaic devices, and light emitting diodes. Appending a 3,4-alkylenedioxy bridge on the heterocycle allows a modified polyheterocycle, where the bridge does not cause an undesirable conformational change in the backbone of the polymer, and the electron donating effect of the oxygen substituents increases the HOMO of the conjugated polymer, reducing both its oxidation potential and its electronic band gap. Poly(3,4-dioxythiophene)s have been extensively studied, poly(3,4-dioxypyrrole)s are somewhat less well known, and poly(3,4-dioxyfuran)s are not well documented.
Poly(3,4-dioxypyrrole)s are materials that display high electronic band gaps and low oxidation potentials, and have properties that make them excellent candidates as sensors, supercapacitors, and electrochromic devices where high conductivity and processability are needed. The syntheses and properties of a wide variety of poly(3,4-dioxypyrrole)s have been reported, for example, in: Walczak et al., Adv. Mater. 2006, 18, 1121-31; Schottland et al., Macromolecules 2000, 33, 7051-61; Sonmez et al., Macromolecules 2003, 36, 639-47; Thomas et al., Adv. Mater. 2000, 12, 222-5; and Walczak et al., Macromolecules 2007, 40, 7777-85.
More recently, the polymerization of 2,5-diodo-3,4-alkylenedioxypyrrole in bulk or using a suitable solvent has been disclosed in Reynolds et al., U.S. Pat. No. 7,649,076 and Walczak et al., Macromolecules 2008, 41, 691-700. By this method, high molecular weight polymer can be prepared without the use of metals, oxidants, solvents, or other additives. Additionally, reaction can be carried out in aqueous solution and tolerates substitution by a wide variety of functionalities, including those that cannot be synthesized by an oxidative polymerization process. This polymerization, as shown in Scheme 1, requires a three-step synthesis that starts from a 3,4-dioxypyrrole-2,5-diacid and requires isolation and purification of the intermediate 2,5-di-iodo-3,4-dioxypyrrole monomer. However, the isolation and purification steps reduce overall yield and throughput. Furthermore, the polymerization process is limited to the types of 3,4-dioxypyrrole monomers reported in Reynolds et al. Hence, a method that does not require the use of 2,5-di-iodo-3,4-dioxypyrrole and can expand the range of 3,4-dioxypyrrole-based monomers that can be polymerized efficiently is desirable.